Steam generating plants



Nov. 6, 1962 R. STARMER ETAL 6 STEAM GENERATING PLANTS Filed March 22, 1960 1550 a2 as flak 2% ama- Inventors GM. 6". Attorneys 3,062,194 Patented Nov. 6, 1952 3,062,194 STEAM GENERATING PLANTS Roy Starmer, Cullercoats, Northumberland, and James Ratcliife Emmett, Ponteland, Northumberland, England, assignors to Richardsons, Westgarth & Co. Limited, Wallsend, England Filed Mar. 22, 1960, Ser. No. 16,767 Claims priority, application Great Britain Mar. 24, 1959 11 Claims. (Cl. 122-1) the make-up water, and is such that most of the steam is condensed by its contact with the water. The small quantity of steam which is not condensed is used to vent the deaerator, and is kept to as low a value as possible since its heat is either lost or degraded. One of the disadvantages of this method is that great care is required to ensure that all the water particles are exposed to the scrubbing action of the limited quantity of steam, as otherwise the deaeration is not complete. It is therefore one of the aims of the present invention to provide means by which a more thorough deaeration of the make-up water is made possible.

According to the invention, a steam-generating plant comprises a boiler connected to a steam inlet in the heatinput section of a flash evaporator by a steam passageway which includes a deaerator having a connection with the boiler for the passage of boiler make-up water.

Such a construction allows the quantity of steam supplied to the deaerator for deaeration of the make-up Water to be greater than that supplied to the deaerator in the prior method described above. This ensures thorough deaeration of the make-up water in all parts of the deaerator. Thereafter, the steam which is not condensed is passed to the heat-input section of the evaporator instead of being vented to atmosphere. Thus, the heat contained in this steam is not wasted nor degraded.

If desired, all the steam which is fed to the heat-input section of the evaporator can be passed through the deaerator. Alternatively, a second steam passage-way between the boiler and the heat-input section can be pro vided so that a portion of the steam fed to the heat-input section passes through the deaerator while the other portion by-passes the deaerator. In each case, however, the total quantity of steam which is passed to the heat-input section should be sufiicient to heat the liquid passing through the heat-input section to the required temperature.

A number of examples of a steam-generating plant in accordance with the invention will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic part-sectional view of one form of plant;

FIGURE 1a is a view illustrating a modification of the plant shown in FIGURE 1;

FIGURE 2 is a similar view illustrating a modification of the plant shown in FIGURE 1; and

FIGURES 3 and 4 are vertical sections illustrating constructional variations.

The evaporator shown in FIGURE 1 comprises a nurmber of adjacent heaters 10 and a number of adjacent flash chambers 12, each flash chamber being associated with a heater and communicating therewith through a passage 14. Alternatively, each flash chamber can be arranged to communicate with its associated heater through a simple aperture 16 in an internal dividing wall 18 common to the associated heater and flash chamber as shown in FIGURE 4. The internal dividing wall 18 in FIGURE 4 lies in a vertical plane, but it may be arranged horizontally, depending on the arrangement of the heater relative to the flash chamber. Two sets of liquid-conveying means are arranged in the heaters, and each set 20 and 22 consists of a single tube which passes through an aperture or apertures provided in one or more partition walls 24 between adjacent heaters. Alternatively, each set may comprise a number of tubes extending between opposite end faces and providing for a number of parallel streams in each set. As a further alternative, each of the liquidconveying means 20 and 22 in each heater may consist of a number of tubes arranged so as to provide a number of parallel streams. Each tube arranged for conveying a stream may consist of a number of tube units connected in series. In this case, the tubes, or the series-connected tube units, constituting the set 29' and the set 22 respectively are joined in series to the respective tubes or tube units in the adjacent heaters.

The tube or tubes 22 serve to convey liquid to be evaporated through the heaters ill in the direction indicated by the arrows. The heated liquid then passes through a heat-input compartment 26 which forms part of the evapo rator and which receives steam as a heating medium through -a tube 28 from a deaerator compartment 30. On leaving the heat-input compartment 26, the liquid passes into the first one of the line of flash chambers 12 and passes from flash chamber to flash chamber through simple apertures 32 formed in internal partition walls 34 separating adjacent flash chambers. In each flash chamher some of the liquid is evaporated, and the vapour thus produced enters the heaters 10 through the passages 14 shown in FIGURE 1 or through the simple apertures 16 shown in FIGURE 4.

The liquid which remains unevaporated leaves the final flash chamber through a tube 36 and passes through a circulating pump 38. From here, part of the liquid is blown down to waste through a blow-down pipe 40, while the bulk is recirculated after fresh liquid, which enters the system through a pipe 42, has been added thereto in order to replace the distilled and discharged quantities.

The vapour which enters the heaters 10 from the flash chambers 12 gives up its heat to liquid passing through the tubes 20 and 22 and is thereby condensed. The condensate forms the distillate which it is desired to produce in the evaporator, and is cascaded from heater to heater through simple apertures 44 in the partition walls 24 separating adjacent heaters. The distillate is removed from the final heater by means of a distillate-extraction pump 46. Alternatively, the distillate may be extracted from each heater individually. Some of the distillate is mixed with condensate which enters the system through a pipe 48. This condensate is from an external source of supply 50 which, for example, may be a steam condenser.

The mixture of condensate from the external source of supply 50 and distillate from the heaters 10 is then passed through the tube or tubes 26 so that the mixture is heated by vapour from the flash chambers 12. After passing through the final heater 10, the mixture is taken to a storage tank or other container 52 which is arranged to supply make-up water to a steam boiler 54 through pipes 56 and 58. The pipe 56 leads into the deaerating compartment 30 so that the make-up water is thoroughly de- 0 aerated by steam which enters the said compartment through a pipe 60 from the steam space of the boiler 54. The deaerated water is fed from the bottom of the com- 3 partment 30 through the pipe 58 to the boiler, and the steam in the compartment 30 which is not condensed by its contact with the make-up water passes into the heatinput compartment 26 through the passage 28.

It will be seen that, in the installation shown in FIGURE 1, the boiler make-up water is derived from distillate produced in the flash evaporator. It is therefore convenient in such an installation for the deaerator 30 to be made an integral part of the evaporator, and where the evaporator comprises a vessel divided internally by partition walls into compartments serving as heaters and flash chambers, one of the compartments will normally be used instead as a deaerator. The disposition of the compartment is not critical, but it is preferably located adjacent the heatinput section 26 of the evaporator so that steam passing through the deaerator 30 can then enter the heat-input compartment 26 by way of a simple aperture 62 (see FIG- URE 3) in the partition wall 18 dividing the deaerator 30 from the heat-input compartment 26 of the vessel.

The installation of FIGURE 1 is designed so that all the steam which is fed to the heat-input compartment 26 is passed through the deaerator 39. However, it is possible to provide a second passage 64 (see FIGURE 161) between the steam space of the boiler 54 and the compartment 26 which by-passes the deaerator. This allows a portion of the steam to be passed through the deaerator 30 while the other portion by-passes the deaerator. Whichever system is adopted, the total quantity of steam which is passed to the heat-input compartment 26 should be sutficient to heat the liquid passing through the said compartment to the required temperature.

FIGURE 2 shows a modification to the steam-generating plant of FIGURE 1. The modification consists in arranging a steam-turbine 64 in the passage 60 between the boiler 54 and the deaerator 36, the remainder of the plant being the same as in FIGURE 1.

It will therefore be seen that the invention allows a comparatively large quantity of steam to be passed through the deaerators 30, with the result that the makeup water is more thoroughly scrubbed and deaerated than in previous arrangements. At the same time, heat losses are reduced to a minimum since the steam or its condensate leaving the deaerator 30 is not discharged to atmosphere but is instead passed into the heat-input section 26 of the evaporator which, in efiect, serves as a condenser for the deaerator. 'It is also advantageous in certain cases for deaerator 30 to be made an integral part of the evaporator vessel, which allows the number of pipe connections and the material required for the walls of the deaerator to be appreciably reduced.

We claim:

1. A steam generating plant comprising a boiler and a flash evaporator, said evaporator comprising a plurality of serially connected heaters, a heat-input chamber connected to said heaters, means conveying liquid to be evaporated, said means passing through the heaters and heat-input chamber in heat exchange relation thereto, a plurality of serially connected flash chambers having outlets connected to the heaters for passing steam thereto, the liquid conveying means having one end connected to at least one of the flash chambers, a boiler make-up water supply, a deaerator connected to said make-up water supply, said deaerator having a make-up Water outlet, the boiler being connected to said deaerator make-up water outlet, a steam outlet connecting the boiler to the deaerator and conduit means for conveying excess steam from the deaerator to the heat-input chamber.

2. A steam-generating plant according to claim 1, in which said boiler is also connected to said heat-input section of said flash evaporator by a second steam passageway which by-passes said deaerator.

3. A steam-generating plant according to claim 1, in which said deaerator is an integral part of said evaporator.

4. A steam-generating plant according to claim 1, in which said deaerator and said heat-input section of said evaporator are located adjacent to each other and have a common dividing wall which separates them from one another.

5. A steam-generating plant according to claim 1, in which a dividing wall separates said deaerator and said heat-input section of said evaporator, said wall having a simple aperture through which steam may pass from said deaerator to said heat-input section.

6. A steam-generating plant according to claim 1, in which said steam passage connection between said boiler and said deaerator includes a steam turbine.

7. A steam-generating plant according to claim 1, in which said evapoartor includes at least one heater provided with two sets of liquid-conveying means, one set being arranged for the passage therethrough of liquid to be evaporated while the other set is arranged for the passage therethrough of distillate produced in said evaporator.

8. A steam-generating plant according to claim 1, in which said deaerator is connected to the delivery end of a set of liquid-conveying means which serve to convey distillate through at least one heater in said evaporator.

9. A steam-generating plant according to claim 1, in which said evaporator comprises a vessel divided by in ternal partition walls into a number of adjacent heaters and a number of adjacent flash chambers.

10. A steam-generating plant according to claim 1, in which said evaporator includes a number of flash cham: bers and a number of heaters, and in which simple apertures are provided inpartition walls in said evaporator whereby to allow the passage of liquid from flash chamber to flash chamber, the passage of distillate from heater to heater, and the passage of flashed vapour from said flash chambers to said heaters.

11. A steam generating plant according to claim 1 in which the boiler make-up water supply is a distillatecollecting section of the evaporator.

References Cited in the file of this patent UNITED STATES PATENTS 1,441,507 Jacobus Ian. 9, 1923 2,944,599 Frankel July 12, 1960 v FOREIGN PATENTS 1,170,434 France Sept. 22, 1958 

